Antenna system



Jan. 3, 1939. J, B DOW 2,142,117 v ANTENNA SYSTEM Filed March 18, 1957 2 Sheets-Sheet 1 INVENTOR JENNINGS B. DOW

BY an w' ATTORNEY J. B. DOW

ANTENNA -sYsTEM Jan. 3, 1939.

Filed March 18, 1937 2 Sheets-Sheet 2 INVENTOR JENNINGS B. DOW- ATTORNEY Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as

amended April 30, 1,928; 370 '.v G. '757) My invention relates to antenna systems in general but more particularly to apparatus for producing an efficient radiating. instrumentality that may be conveniently adjusted from a distance by simple means. My invention comprehends certain new elements, and combinations of new and old elements, and the method of operating same.

One of the objects of my invention is to prol0 vide an eiiicient adjustable antenna for radio sending and receiving stations.

Another object of my invention is to provide a simple and inexpensive means for adjusting my antenna from a distance.

l5 Another object of my invention is to provide in combination the means for readily matching the antenna impedance to that of the transmission line for the efcient operation of the sending and receiving system.

A still further object of my invention is to provide a simple combination of transmitter (or receiver), transmission line and adjustable antenna to produce a highly efficient system as a whole,

Other and further objects oi my invention will be apparent from the following specification. .For simplicity, my invention will be described with particular reference to its use for radio transmission. No limitations are desired to be placed upon its use, since it is equally applicable to radio receiving systems as will be well understood by those skilled in the art. Moreover, while the transmission lines which I shall describe are of the concentric type in the preferred embodiment of my invention, it will be understood that any of the other types of lines may be used, in which event the gas or fluid pressure would be supplied for adjusting the antenna throughV any suitable arrangement.

In the drawings:

Fig. 1 shows one form of my invention in which a column of mercury or other conducting fluid in a tube is employed as an antenna, in combination with a suitable arrangement for adjusting the antenna length by means of gas pressure introduced through a concentric transmission line.

Figs. 1a and 1b are cross section views on the lines Ia--Ia and Ill-lb, respectively, Fig. 1.

Fig. 2 shows one form which the input end of the transmission line may take in supplying electrical energy and gas pressure through the line to the antennas of Figs. 1 and 3.

Fig. 3 is a top plan view of another form which the antenna portion may take.

Fig. 3a is a side View of the device shown in Fig. 3, with parts in section on line 3dr-3a, Fig. 3.

Fig. l shows a mercury column I in an insulating tube 2 mounted upon a support 3 and a transmission line 4-5 having an outer conductor 4 and an inner conductor 5. The tube 2 may be of composite construction in which the upper section 2 is made of insulating material and the lower section 6 and mercury reservoir 10 l are made of conducting material. If the lower section E is made of conducting material, it is preferable that it be constructed of a substance which does not form an amalgam with the mercury. Other conducting fluids may obviously be 15 employed in lieu of mercury.

The base 3 is preferably made of an insulating material such as porcelain; however, the requirements of the base may be met by a composite construction in which only a portion is insulat- 20 ing material. In the form of my invention shown in Fig. l, the transmission line terminates physically in the base 3. The inner conductor of the line extends through the insulated base 3 in such manner as to provide an electrical path 25 to the mercury reservoir l. An insulating tube extends from the outer conductor 4 for the purpose of applying gas pressure to the mercury surface. Gas is conducted from a suitable point, preferably at the radio transmitter, through the 30 transmission line 4-5 and tube 8 for raising or lowering the mercury column l to the desired height. The tube 2 is preferably terminated at the top with a chamber 9 which may be partially evacuated or may contain gas under some 35 pressure. The upper end of transmission line il should be sea-led gas-tight and terminated electrically in a system of conductors ID to provide a ground plane for the antenna comprising the mercury column. If the lower section 6 of tube 40 2 is of conducting material, this section forms a portion of the antenna.

In the preferred embodiment of my invention,

I make the length of the antenna one-quarter wave length by adjusting the gas pressure, and 45 employ a transmission line having a characteristie impedance corresponding approximately to the radiation resistance of the antenna. It is preferable that the antenna be adjusted to a length corresponding approximately to any odd 50 number of quarter wave lengths of the space wave. The actual length for most efficient operation is a critical function of the radio frequency employed, and hence, it becomes desirable to provide pressure adjusting means capable 55 of close adjustment in order to realize all the benefits to be derived. It is, of course, possible to arrange my invention to incorporate antennas having a length corresponding to an even number of quarter wave lengths but this involves some design complications.

Fig. 2 shows a portion of the nal stage of a radio transmitter ii having an amplifying tube I2 the anode i3 of which is connected through output circuit lll-i5 to a high voltage source I through a current indicating device Il. The output circuit is coupled or connected to the inner conductor 5 of the transmission line 5 5. Outer conductor 4 is shown grounded at I8 as is customary when employing concentric transmission lines. Transmission line li--S is sealed gas tight by an insulating device i9. Means are provided at 2G for admitting gas from tank 2! to the transmission line 12-5 for varying the pressure in the line to adjust the height of the antenna of Fig'. l. The valve 2G may be a three-way valve whereby gas may be introduced into member i or may be released therefrom to the atmosphere. Pressure indicating means 22 be calibrated in terms of antenna height. Final adjustment of antenna height is most efiiciently accomplished by varying the gas pressure to adjust the mercury column and noting the reading of current indicator i'l. An alternative source of gas is shown by pipe connection 23 through regulating valve 2d. I have found it desirable to use dry compressed nitrogen or carbon dioxide as a gas, as these are usually employed in concentric lines to keep out moisture. Any dry gas or even an insulating liquid may be employed if desired.

If it is desired to employ an open type of transmission line, one of the conductors may be made of tubing for applying the gas pressure for adjusting the antenna, or a separate tube may be used in conjunction with the line for applying the gas pressure.

Fig. 3 shows another form which my antenna may take. This comprises an S-shaped tube 25 of insulating material containing a U-shaped mercury column 22S-22K Gas pressure is applied through the transmission line @-5 to mercury surface at 2G through path 2B and serves to vary the height of the longer section of the mercury U which section, for all practical purposes. determines the antenna height. A. connection 3i) from the inner conductor 5 of transmission line 4 5 is made to the bottom of the mercury U. The outer conductor i of the transmission line terminates in the ground plane conductors iii.

It will be apparent-that my antenna system lends itself to efficient use, especially at very high frequencies where it is often necessary to locate the antenna at a considerable distance from the transmitter or receiver with which it is employed. Such installations are often very costly owing to the long length of transmission line required and a single simple system capable of adjustment to any one of several frequencies required to meet the daily and seasonal communication problem lls a definite need.

While I have described my invention in certain preferred embodiments, it will be understood that modications may be made and that no limitations are intended other than those imposed by the scope of the appended claims.

The invention herein described and claimed may be used and/or manufactured by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What I lclaim as new and desire to secure by Letters Patent of the United States is:

l. An antenna system comprising in combination an insulating tube, a column of conducting liquid having radiation resistance therein, a transmission line having at least two conductors terminating near said column, said transmission line having a characteristic impedance substantially equal to the radiation resistance of said column, and an electrically conductive connection between said column and one of the conductors of said transmission line.

2. An antenna system in accordance with claim l that includes a reservoir for said liquid and means for varying the heightl of said column by applying gas pressure to the surface of the liquid in said reservoir.

3. An antenna system in accordance with claim l. that includes a reservoir for said liquid and means for varying the height of said column, said means comprising a gas pressure connection between one of the conductors of said transmission line and additional means for applying gas pressure Alhrough that conductor of said transmission line last mentioned to the surface of the liquid in said reservoir.

fi. An antenna system in accordance with claim l including means operated by gas pressure for varying the height of said column.

5. An antenna system in accordance with claim l wherein said transmission line comprises two concentric conductors and means for applying gas pressure through one of said conductors for varying the height of said column.

6. An antenna system comprising a U-shaped column of conducting liquid, an insulating tube in which said column is contained, a connection between said column and the source of high frequency energy and means for applying pressure to the surface of the conducting liquid in one side of said column for raising or lowering the other side of said column.

7. In a wave signaling system having an adjustable antenna and a. transmission line feeding high frequency energy to said antenna, said line comprising at least in part a hollow gas containing conductor, the method of adjusting said antenna which consists in varying the gas pressure in said conductor.

8. A radio antenna, comprising a radiating static column of electrically conducting fluid having radiation resistance, and fluid pressure means for varying the effective length of said column.

9. A radio antenna, comprising a substantially U-shaped radiating static column of electrically conducting fluid having radiation resistance, and fluid pressure means to act upon one leg of said column to vary the effective length of said column.

l0. A radio antenna, comprising a radiating static coliLnn of electrically conducting fluid and means to vary the length of said column.

JENNINGS B. DOW. 

